Chapter 1: Introduction to the EIU 37DMS-100 Family EIU User Guide TELECOM12The Ethernet address in the LIUINV table has the format of the NortelSuperNode family range of addresses: X000075Fxxxxx, where X ishexadecimal notation and x is a variable. For more information on MACaddresses, refer to “Appendix I: Obtaining a MAC address”.Diagnostics for the EIU test only the Ethernet interface card (EIC) and theEthernet interface paddle board (EIP). These diagnostics do not test the AUIcable. The AUI cable attaches to the paddle board and to a connector in thebulkhead. An extension of the AUI then runs from the bulkhead to the MAU.Diagnostics also test the MAU. EIU diagnostics test the EIU’s connectivity tothe AUI and the MAU up to the HUB.Lastly, the record start command cannot be initiated during a telnet session onthe connected device.Limitations associated with protocolsTrailers are not supported. Trailers are the field on the data packet in which thesystem places the “headers”, which normally precede the data, after the data.Trailers can be negotiated between cooperating systems in an attempt toimprove efficiency.In the DMS-core, the protocol stack runs in the SuperNode IP (SNIP)scheduler class. This includes the IP receive processes and timer functions forTCP. In all other nodes, the protocol stack runs in CP class. The initialallocation for SNIP class is 3 percent and an interface is provided that allowsan application to modify this value.The following sections describe specific limitations associated with protocols.Routing information protocolThe size of the dynamic routing table is limited to 436 entries. This limitationis imposed by the current implementation of and the current number of buffermanagement system (BMS) buffers reserved for routing information protocol(RIP) broadcasts. If the routing table overflows the routes at the end of the RIP,the system ignores the messages. This situation can lead to unpredictablerouting behavior, such that routes may appear and disappear every 30 s. Thereis no warning log to notify the operating company that this errant behavior isoccurring.RIP Version 1.0 does not support variable-length subnetting. This limitationmeans that all subnets that use RIP to exchange routing information must usethe same number of bits in their IP address to identify their subnet. If a subnetdoes not adhere to this rule, unpredictable and intermittent loss-of-connectivity behavior may be experienced on the EIU. RIP-II, which supportsvariable-length subnetting, is not implemented on the EIU.
